I have a question about 'when' in following sentence;
"There will be humans back on Mars in about four years when the area 4 mission team arrives."
While I'm inclined to consider it a relative adverb, I'm not sure if the relative adverb can take "in about four years" (prepositional phrase) as an antecedent. If so, this where should be an a subordinate conjunction, leading an adverb clause.
Would hope to get your clarification.
Thanking and Best RGDS,